In 1994, telomerase activity was discovered in human cancer cell lines. Although telomerase is not active in human somatic tissue, human somatic cells do contain the genes for telomerase proteins and telomerase RNA. Since inappropriate activation of telomerase may contribute to cancer, why do you think the genes coding for this enzyme have been maintained in the human genome throughout evolution? Are there any types of human body cells where telomerase activation would be advantageous or even necessary? Explain.

In 1994, telomerase activity was discovered in human cancer cell lines. Although telomerase is not active in human somatic tissue, human somatic cells do contain the genes for telomerase proteins and telomerase RNA. Since inappropriate activation of telomerase may contribute to cancer, why do you think the genes coding for this enzyme have been maintained in the human genome throughout evolution? Are there any types of human body cells where telomerase activation would be advantageous or even necessary? Explain.

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter13: An Introduction To Genetic Technology

Section: Chapter Questions

Problem 11QP: Cloning Genes Is a Multistep Process In cloning human DNA, why is it necessary to insert the DNA...

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If you knew the mRNA sequence for the human insulin gene could you know what size cDNA fragment you would find on your DNA gel when you ran it against a size standard (a “molecular ruler”)? Would you continue with your insulin cloning experiment, if the DNA from your PCR was very different in size from that predicted by the insulin mRNA? Why or why not? Primers can sometimes bind and target the wrong gene, especially if the primers are allowed to bind to the DNA strands at a low temperature. PCR also preferentially amplify short segments of DNA. Would it be important to actually run the cDNA after the PCR on a DNA gel in order to check for a PCR product of the predicted size for the insulin gene? Why or why not?
Why do adult human cells (other than germ cells and stem cells) NOT express the enzyme telomerase? In other words what benefit does not having telomerase provide to these cells?
The enzyme telomerase is part protein and part RNA. What would be the most likely effect of a large deletion in the gene that encodes the RNA component of telomerase? How would the function of telomerase be affected?
In contrast with the genomic manipulations of animals and plants described in this chapter, human genetherapy is directed specifically at altering the genomes of somatic cells rather than germ-line cells.Why couldn’t or wouldn’t medical scientists try to alter the genome of human germ-line cells?
If I clone a complete eukaryotic gene, including the eukaryotic promoter region, ligate it into a plasmid, and transform it into E. coli, will I be able use the transformed E. coli to make the corresponding protein? Explain why, or why not? If you decide to do this, what would your cloning strategy be?
Mice that are engineered to block expression of the gene coding for telomerase protein age at a much faster rate than normal and have a decreased life span. The results of these mice experiments led researchers to propose that treatments that could lead to overexpression of the telomerase gene might serve as the “fountain of youth” leading to reversal of aging in humans. Why should we be very cautious about trying such treatments? Why it might be advantageous for multicellular organisms for most of their somatic cells not to express telomerase?
It is possible to take the DNA of a gene from any source and place it on a chromosome in the nucleus of a yeast cell. When you take DNA of a human gene and put it into a yeast cell chromosome, the yeast cell can synthesize the human protein. However, when you remove the DNA for a gene normally present on yeast mitochondrial chromosomes and put it on a yeast chromosome in the nucleus, the yeast cell cannot synthesize the correct protein, even though the gene comes from the same organism. Explain. What would you need to do to ensure that such a yeast cell could make the correct protein?
In 1995, Hamilton Smith, Craig Venter and co-workers published the first complete genome sequence of a self-sustaining organism, that of the bacterium Haemophilus influenzae. Analysis of the genome sequence revealed that the organism does not have a gene that could encode a telomerase enzyme. What is the potential evolutionary consequence of this? Explain your answer.
Do a few cells created by therapeutic cloning of your own somatic cells constitute life? If these cells do constitute life, do they have the same rights as a human being conceived naturally? If it were possible, should someone be allowed to grow his or her own therapeutic clone into an adult?
In yeast cells, telomerase remains active and maintains telomeres of about 300 base pairs. Propose what would happen to the telomeres over time in a yeast lineage in which the following mutations were created. a) The gene encoding the catalytic subunit of the telomerase is deleted. b) The template portion of the telomerase RNA is changed from 5’-ACACCCACA to 5’-ACAUCUACA.
n yeast cells, telomerase remains active and maintains telomeres of about 300 base pairs. Propose what would happen to the telomeres over time in a yeast lineage in which the following mutations were created. The gene encoding the catalytic subunit of the telomerase is deleted.
In yeast cells, telomerase remains active and maintains telomeres of about 300 base pairs. Describe how the telomeres would change over time in a yeast lineage after the following mutations were created. a. The gene encoding the catalytic subunit of the telomerase is inactivated. b. The template portion of the telomerase RNA is changed from 5’-ACACCCACA to 5’-ACAUCUACA.